V-belt drive systems wherein both the driver sheave (motor pulley) and the driven sheave (fan pulley) were made of metallic material and whereby said V-belt drive system was used in a corrosive atmosphere have been known previously.
This atmosphere is commonly encountered in cooling towers or other type evaporative water-to-air heat exchangers where the fan and drive mechanism is located directly in the outgoing moist air stream. In fact, in this type of cooling tower atmosphere where the drive system would be located, the air is mildly heated and highly humidified by the cooling tower recirculating water. Additionally the cooling tower air usually accumulates and circulates drift (water carryover) particles which can contain chemical additives and salt concentrations and are usually highly corrosive to lower-cost metals. Also, when used in a cooling tower atmosphere during fan off-cycles, this region is encompassed in a fog-like mist of corrosive vapors which emanate from the cooling tower chambers.
The problem of preventing corrosion of this type V-belt drive system was solved in the past by totally encasing the entire drive system in a vented enclosure. In this case, both driver and driven sheaves were made of cast iron or steel. The disadvantages of this system were that one could not see the V-belt or drive belt and that large and cumbersome components which were part of the vent enclosure had to be removed when inspecting or changing the belts. In addition air flow can be restricted by the vented enclosure which normally is directly beneath the fan.
Applicants' invention relates to the use of a V-belt drive system using a non-metallic driven sheave and a metallic driver sheave wherein the non-metallic driven sheave is larger than the metallic driver sheave and the metallic driver sheave may be enclosed in a vented chamber which is ventilated with fresh ambient air by action of the fan system served by said V-belt drive system.